This invention relates to bats such as baseball bats and the like, including toy bats having improved strike surface properties. This invention also relates to a combination of such bats with balls having similar surface properties. More specifically, this invention relates to bats having selected strike surface roughening characteristics which promote the tendency of a ball to spin when struck off-center or struck a glancing blow by the bat. The promotion of such tendency to spin enhances the tendency of the trajectory of the ball, after being so struck, to deviate from the trajectory that would be expected if the tendency of the ball to spin were not thus enhanced. Incorporating such surface properties into the ball enhances the effect created by the bat.
Much effort has been directed in the past to improving bats, such as baseball bats, so that batsmen are less likely to hit foul and more likely to hit fair and safe. Examples of bats developed for such purposes are set forth in U.S. Pat. Nos. 1,530,427; 838,257; 805,132; and 771,247. Unless the leading edge of the bat strikes the ball and, preferably, is perpendicular to the flight path of the ball, the blow will, in some degree, be a glancing blow which, in turn, tends both to make the ball rebound off the bat at an angle and to make the ball spin. Such spin is greater the greater the friction between the bat surface and the ball surface and is less the less the friction between the bat surface and the ball surface. Spin brings into play forces, such as the Magnus and anti-Magnus forces described at length in my U.S. Pat. No. 4,438,924, which cause the trajectory of the ball to deviate from the trajectory expected if the ball were not spinning or were spinning at a different speed of rotation, spinning on a different axis of rotation, or both.
The batter often knows that he has not hit with the leading edge of the bat or not hit perpendicular to the flight path of the ball by both the initial direction of rebound off the bat and the effect on the flight path of the spin that the ball then possesses. The greater the spin of the ball, the greater the chances that the batter will be aware of so striking the ball because of the resulting pronounced deviation from the expected trajectory of the ball.